Pfizer Inc. (PFE)’s anti-smoking drug Chantix produced a higher rate of heart attacks or strokes in patients using the treatment than those who didn’t take the product, according to an analysis of clinical trials. The number of cardiovascular issues in patients on Chantix and those who took a placebo was uncommon, the U.S. Food and Drug Administration said today in a safety notice on its website. While the increased risk wasn’t statistically significant for those on Chantix, it seems “more likely that it is related to the drug and not purely a chance finding,” the agency said. Chantix carries a warning that it raises the risks of suicide and may be tied to higher heart danger in patients with cardiovascular disease. The warning label had been changed last year after regulators cited the heart concerns and asked New York-based Pfizer to further evaluate the risks with a large analysis of existing studies of the drug. The agency’s announcement today followed that analysis. Of 4,190 Chantix users, 13 were found to have experienced a major cardiovascular event such as heart attack or stroke compared with six of 2,812 who took a placebo in 15 Pfizer- sponsored clinical trials, the FDA said. The benefits of Chantix outweigh the risks, MacKay Jimeson, a spokesman for Pfizer, said in an e-mail. “The benefits of quitting smoking are immediate and substantial,” Jimeson said. “Chantix has been demonstrated to increase the likelihood of abstinence from smoking for as long as one year compared to treatment with placebo.” Smoking is a major risk factor for heart disease, the FDA said. Patients taking Chantix should contact their doctor if they experience new or worsening symptoms of cardiovascular disease, such as chest pain, shortness of breath, calf pain or sudden onset of weakness, numbness or difficulty speaking. Chantix generated $720 million in sales last year for Pfizer, the world’s largest drugmaker, according to data compiled by Bloomberg. The FDA notice said that about 2.3 million Chantix prescriptions were dispensed in the year ended in September.